[PATCH] D116678: [3/4][RISCV][MC] Teach MCInstrAnalysis::evaluateBranch to determine the target of an auipc+jalr

[Alex Bradbury via Phabricator via llvm-commits]

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Now that MCInstrAnalysis takes a previousInst argument, it can be used
to determine the target of a pair of auipc+jalr instructions.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116678

Files:
  llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
  llvm/test/tools/llvm-objdump/ELF/RISCV/branches.s


Index: llvm/test/tools/llvm-objdump/ELF/RISCV/branches.s
===================================================================
--- llvm/test/tools/llvm-objdump/ELF/RISCV/branches.s
+++ llvm/test/tools/llvm-objdump/ELF/RISCV/branches.s
@@ -56,12 +56,12 @@
 # CHECK: 46: c.j 0x60 <bar>
 c.j bar
 
-# CHECK: 48: auipc ra, 0
-# CHECK: 4c: jalr	ra, 16(ra)
+# CHECK: 48: auipc	ra, 0
+# CHECK: 4c: jalr	ra, 16(ra) <foo+0x58>
 call .Llocal
 
-# CHECK: 50: auipc ra, 0
-# CHECK: 54: jalr	ra, 16(ra)
+# CHECK: 50: auipc	ra, 0
+# CHECK: 54: jalr	ra, 16(ra) <bar>
 call bar
 
 .Llocal:
Index: llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
===================================================================
--- llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
+++ llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCTargetDesc.cpp
@@ -142,6 +142,14 @@
       return true;
     }
 
+    if (Inst.getOpcode() == RISCV::JALR && PreviousInst.hasValue() &&
+        PreviousInst->getOpcode() == RISCV::AUIPC &&
+        PreviousInst->getOperand(0).getReg() == Inst.getOperand(1).getReg()) {
+      Target = Addr + Inst.getOperand(2).getImm() +
+               PreviousInst->getOperand(1).getImm() - 4;
+      return true;
+    }
+
     return false;
   }
 };


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